For a glycol system using hot water as its heat source which of the following statements is false?

For a glycol system using hot water as its heat source which of the following statements is false?

a) Valve V-3 will be opened to feed a constant flow of hot water to the converter.
b) Hot water temperature should not exceed 100 degrees C.
c) Temperature controller TC-1 opens V-3 when the temperature outside drops to 10 degrees C.
d) Flow Switch FS automatically starts the glycol pump automatically after V-3 is opened.
e) Provide flanges or unions and manual shutoff valves to facilitate coil removal.






Answer: D

Air vents are

Air vents are

a) not required when an inverted bucket steam trap is used
b) not required on the steam mains if an inverted bucket steam trap is used at the steam coil
c) not required at the steam coil if a float and thermostatic (F & T) trap is used at the steam coil with an atmospheric return and the steam main is adequately vented
d) not required anywhere if a float and thermostatic (F & T) trap is used at the steam coil
e) required only with hot water coils

Answer: C

Which of the following steam traps are preferred for use with steam coils operating at low and medium steam pressure?

Which of the following steam traps are preferred for use with steam coils operating at low and medium steam pressure?

a) inverted bucket
b) dynamic
c) F & T trap (float and thermostatic)
d) thermostatic only
e) none of the above






Answer: C

Steam coil piping and trapping

Steam coil piping and trapping

a) is the same as for hot water and glycol coils
b) only handles steam and non-condensable gases
c) differs from the hot water and glycol coil because it carries more fluids: steam, air, water, and non-condensable gases
d) are installed in the horizontal position whenever possible
e) can be supported directly by the coils

Answer: C

The greatest fears in hot water coil installations handling subfreezing air are: i) pipe expansivity ii) outside air temperature being too low iii) failure of the circulating pipe iv) water viscosity being too high v) failure of the heat source

The greatest fears in hot water coil installations handling subfreezing air are:
i) pipe expansivity
ii) outside air temperature being too low
iii) failure of the circulating pipe
iv) water viscosity being too high
v) failure of the heat source

a) i, ii, and iv
b) i, ii, and iii
c) iii only
d) i, iv, and v
e) iii and v






Answer: E

A thermostat which is sometimes installed in the return air duct serves which main function?

A thermostat which is sometimes installed in the return air duct serves which main function?

a) To limit temperature of the heated outside air
b) To control the throttle of the steam in the tubes
c) To sense the temperature of the steam in the coils
d) To minimize temperature fluctuations in discharge air
e) To heat recirculated air





Answer: D

The use of ethylene glycol solution will result in which of the following: i) Lower heat transfer rate ii) Better protection against freezing iii) Increased friction losses in the coil and piping iv) The requirement of a larger pump with more horsepower

The use of ethylene glycol solution will result in which of the following:
i) Lower heat transfer rate
ii) Better protection against freezing
iii) Increased friction losses in the coil and piping
iv) The requirement of a larger pump with more horsepower

a) i and iv
b) i and iii
c) i and iv
d) iii only
e) i, ii, iii, and iv







Answer: E

The flow arrangement best suited for hot water coils is

The flow arrangement best suited for hot water coils is

a) the counterflow arrangement because it is more efficient
b) the parallel flow arrangement because it gives better protection against freezing
c) one in which the cold air enters the coil where the coldest water is flowing
d) the half serpentine
e) the triple bypass flow arrangement






Answer: B

Which of the following is not a cause of freezing in hot water coils?

Which of the following is not a cause of freezing in hot water coils?

a) failure of the circulating pump
b) very low circulating water velocity
c) very high circulating water velocity
d) failure of the heat source
e) poor air venting of the coil






Answer: C

Steam coils with long tube lengths:

Steam coils with long tube lengths:

a. Have the greatest freezing problems at extremely low temperatures such as -35°C
b. Have the greatest freezing problems at temperatures of about -2°C to -1°C
c. Have freezing problems at any temperature
d. Are less likely to freeze than steam coils with short tube lengths
e. Are not likely to freeze at any temperature




Answer: B

Modulating control valves:

Modulating control valves:

a. Are never used to control steam coils, regardless of inlet air temperature
b. Are used for steam coils where the condensate must be lifted to an overhead condensate return line
c. Is used for steam coils when the entering air temperature is below 1.5°C
d. Can be used to control steam coils when the entering air temperature is above 1.5°C
e. Should be oversized






Answer: D

The purpose of the "freeze-stat" temperature controller used with hot water coils is to

The purpose of the "freeze-stat" temperature controller used with hot water coils is to

a. Close the outside air dampers and stop the fan if the heat source fails or the low limit temperature controller malfunctions
b. Prevents coil freeze-up by increasing the hot water flow through the coil to a maximum if the outside air temperature is too low
c. Increase the heat source temperature if the outside air temperature decreases
d. Shut off all water flow to the coil if a freeze condition is detected
e. Increase the fan output if the return air temperature is too low







Answer: A

The purpose of a vacuum breaker used with steam heating coils is to:

The purpose of a vacuum breaker used with steam heating coils is to:

a. Prevent freezing caused by a vacuum or negative pressure in the steam coil
b. Ensure negative air pressure in the conditioned space
c. Prevent excessive temperatures within the steam coil
d. Ensure proper operation of the steam control valve
e. Prevent flashing of the condensate within the steam coil






Answer: A

Ethylene glycol used in glycol coils:

Ethylene glycol used in glycol coils:

a. Has a higher heat transfer efficiency than hot water
b. Has less friction losses in the coil and piping than hot water
c. Requires a smaller pump and less horsepower than hot water
d. Has much lower pressure drops through the coil and piping
e. Has a lower heat transfer efficiency than hot water







Answer: E

To prevent freezing of the steam coil when steam pressure at the coil inlet is too low, or is lost:

To prevent freezing of the steam coil when steam pressure at the coil inlet is too low, or is lost:

a. A second preheat coil is installed at the outside air inlet
b. A modulating steam control valve is installed at the coil inlet
c. A two-position steam control valve is installed at the coil inlet
d. Provisions are made to stop the fan and close the outdoor air dampers
e. Inverted bucket steam traps must be used






Answer: D

Of the following, which would be the greatest concern in the operation of a hot water heating coil, which handles extremely cold air?

Of the following, which would be the greatest concern in the operation of a hot water heating coil, which handles extremely cold air?

a. Excessive pipe expansion
b. Low outside air temperature
c. circulating pump failure
d. failure of a return air fan
e. excessive coil face velocity






Answer: C

The inverted bucket steam trap, as applied to steam heating coils,

The inverted bucket steam trap, as applied to steam heating coils,

a. Is used when the coil steam pressure is higher than 172 kPa or 25 psig
b. Is used when considerable air venting is required
c. Does not require a strainer
d. Is recommended when condensate flows by gravity into a return main at atmospheric pressure
e. Is more expensive than a Float and Thermostatic trap





Answer: A

It is good design practice to select a steam coil size so that:

It is good design practice to select a steam coil size so that:

a. 100% of the coil capacity is needed when the air temperature entering the coil is -1°C
b. At least 40% of the coil capacity is needed when the air temperature entering the coil is -1°C
c. At least 80% of the coil capacity is needed when the air temperature at the coil inlet is -1°C
d. At least 10% of the coil capacity is needed when the air temperature at the coil inlet is -5°C
e. It is twice the size that is required to handle the heating load







Answer: B

The purpose of a flow switch installed in a hot water supply line to an air-handling unit is to

The purpose of a flow switch installed in a hot water supply line to an air-handling unit is to

a. Stop the fan and close the outside air dampers if the low limit temperature controller malfunctions or the heat source fails
b. Open the outside air dampers wide when the water flow is established
c. Open the hot water supply valve further if the hot water flow drops below a safe limit
d. Close the outside air dampers and stop the fan if the flow of water is interrupted, to protect the coil from freezing
e. Alert the operator of a low flow condition







Answer: D

Steam coils with a short tube length of 1.1 m or less, in comparison to steam coils with long tube lengths,

Steam coils with a short tube length of 1.1 m or less, in comparison to steam coils with long tube lengths,

a. are more likely to freeze, even if the steam trap is properly chosen
b. are less likely to freeze regardless of steam trap choice and coil installation
c. must use 2-position steam valves to prevent freeze-up
d. are less likely to freeze if the steam trap is properly chosen and the coil is properly piped
e. will only freeze if the inlet air temperature drops to below -35 degrees Celsius







Answer: D